Electronic pens, otherwise known as digital pens or digital electronic pens, are writing implements that typically have certain writing capabilities and also include certain electronics such as, for example, imaging devices. These devices typically include a single ink cartridge, an imaging sensor such as a camera, electronic circuitry, and so forth. In some instances, these devices may also include electronics for wirelessly communicating with a computing device according to a communication standard such as 802.15 (i.e., WPAN) or other standards. When these devices are used by a user, these devices typically provide data to a computing device such as a personal computer. The data provided to the computing device may be used in order to record the drawing or writing strokes of the user or for other reasons.
For example, one way to use an electronic pen is to use it with a specially treated paper that has been formatted with embedded data that allows the computing device to track the movement of the pen, and more particularly, the nib of the pen, with respect to the paper. The paper may be printed with embedded data in the form of an array of dots that may be substantially or totally invisible to the naked eye. The dots are typically placed at regular intervals on the sheet. Additional microdots may also be printed around the larger dots that provide the locations of the dots with respect to the paper. When a user uses an electronic pen to write or draw on such a paper, the electronic paper using its image sensor may track its relative movement with respect to the paper by reading the embedded data that comes within the field of vision of the imaging sensor. In doing so, the relative writing or drawing strokes of the user may be captured.
Conventional electronic pens tend to be relatively big and bulky due to the presence of all the electronics that are needed in order to perform their basic functions. These devices are constrained to a limited number of functions or features. And because of the amount of electronics already included in these devices, there is minimal amount of space available for including additional components. As a result, these conventional electronic pens typically do not have extra space to hold additional ink cartridges, much less mechanisms for deploying the additional cartridges. There is known in the field of non-electronic traditional writing implementations (e.g., ballpoint pens), multi-pens or multi-ink pens that typically include multiple ink cartridges. Some of these multi-pens employ a twist mechanism to selectively extend or deploy each of the ink cartridges. However, such features are not available in current electronic pens because the space needed in the pen housing for such mechanisms or for the multiple cartridges is unavailable due to the large amount of space already taken up by the various electronics.